Trying again to fail-first

For constraint satisfaction problems (CSPs), Haralick and Elliott [1] introduced the Fail-First Principle and defined in it terms of minimizing branch depth. By devising a range of variable ordering heuristics, each in turn trying harder to fail first, Smith and Grant [2] showed that adherence to this strategy does not guarantee reduction in search effort. The present work builds on Smith and Grant. It benefits from the development of a new framework for characterizing heuristic performance that defines two policies, one concerned with enhancing the likelihood of correctly extending a partial solution, the other with minimizing the effort to prove insolubility. The Fail-First Principle can be restated as calling for adherence to the second, fail-first policy, while discounting the other, promise policy. Our work corrects some deficiencies in the work of Smith and Grant, and goes on to confirm their finding that the Fail-First Principle, as originally defined, is insufficient. We then show that adherence to the fail-first policy must be measured in terms of size of insoluble subtrees, not branch depth. We also show that for soluble problems, both policies must be considered in evaluating heuristic performance. Hence, even in its proper form the Fail-First Principle is insufficient. We also show that the “FF” series of heuristics devised by Smith and Grant is a powerful tool for evaluating heuristic performance, including the subtle relations between heuristic features and adherence to a policy

Measurement procedures affect the interpretation of metatarsophalangeal joint function during accelerated sprinting

This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Sports Sciences on 7/8/2012, available online: http://wwww.tandfonline.com/10.1080/02640414.2012.713501The metatarsophalangeal joint (MPJ) is a significant absorber of energy in sprinting. This study examined the influence of MPJ axis choice and filter cut-off frequency on kinetic variables describing MPJ function during accelerated sprinting. Eight trained sprinters performed maximal sprints along a runway. Three dimensional high-speed (1000 Hz) kinematic and kinetic data were collected at the 20 m point. Three axis definitions for the five MPJs were compared. MPJ moments, powers and energies were calculated using different filter cut-off frequencies. The more anatomically appropriate dual axis resulted in less energy absorbed at the MPJ compared to the oblique axis which also absorbed less energy compared to the perpendicular axis. Furthermore, a low cut-off frequency (8 Hz) substantially underestimated MPJ kinematics, kinetics and the energy absorbed at the joint and lowered the estimate of energy production during push-off. It is concluded that a better understanding of MPJ function during sprinting would be obtained by using an oblique or anatomically appropriate representation of the joint together with appropriate kinematic data sampling and filtering so that high frequency movement characteristics are retained.This article was submitted to the RAE2014 for the University of Chester - Sport and Exercise Sciences, Leisure and Tourism

Grocery Stores Are Not Associated with More Healthful Food for Participants in the Supplemental Nutrition Assistance Program

Background: Despite interventions to improve the nutrition of grocery store purchases, also referred to as at-home (AH) foods, by participants in the Supplemental Nutrition Program (SNAP), little is known about what proportion of participants’ intake is from AH foods and how the dietary quality of AH food compares with participants’ away-from-home (AFH) food. Although recent research indicates SNAP participants have dietary quality that is slightly worse than that of income-eligible nonparticipants, it is unknown whether this is attributable to AH or AFH consumption. Objective: The objective of this study is to examine differences in self-reported dietary intake by food source for SNAP participants compared with income-eligible nonparticipants using 2011-2014 data from the National Health and Nutrition Examination Survey (NHANES). Design: This study included data from the NHANES, a cross-sectional, nationally representative survey of the United States population. Study participants: This study included 2,523 adults with low incomes (≤130% of the federal poverty level) in NHANES (2011-2014). Main outcome measures: Self-reported intake of calories, solid fats, added sugars, and servings of nonstarchy vegetables, whole fruits, and whole grains was assessed by food source in SNAP participants and income-eligible nonparticipants. Statistical analysis: Multivariate linear regression was used for each outcome, controlling for relevant sociodemographic characteristics. Data were stratified by food source, including grocery stores, sit-down restaurants, and fast food. Results: SNAP participants had a higher intake of solid fats and added sugar from AH foods than nonparticipants. Added sugar from AH food accounted for 15.3% of total calories consumed by SNAP participants, compared with 11.8% for nonparticipants (P<0.001). SNAP participants consumed fewer calories from sit-down restaurants, but both groups consumed similar amounts of calories from fast food. Consumption of nonstarchy vegetables, whole fruits, and whole grains was low for both groups. Conclusions: SNAP participants had poorer diet quality from consumption of AH food than did nonparticipants. Future research should focus on interventions to improve the healthfulness of grocery store purchases as a mechanism to improve dietary quality of SNAP participants

Using the Mixed Newton-Euler Formulation in the Orientation Control of Flexibly Mounted Bodies

Extended bodies whose own flexibility may conditionally be neglected can often be faithfully treated directly by any of several formulations based on classical dynamics. Here, the mixed approach employing the Newton-Euler equations for centroidal body-fixed frames will be used, where the absolute angular orientation will be computed via the associated kinematic differential equations relating the rotation matrix with the angular velocity vector. As an example of the practical (but restricted) use of simplified classical methods - and of the computationally attractive mixed Newton-Euler ODE formulation - the mathematical model of the U.S. Army's MLRS-ILMS mechanical launcher is described which is automatically controlled to simultaneously rotate about nonintersecting, nominally vertical and horizontal axes when commanded to target absolute angular orientation coordinates.Center for Electromechanic

Outcomes of primary and recurrent inguinal hernia repair with prosthetic mesh in a single region over 15 years

Background Sutured inguinal hernia repairs are now uncommon, with evidence suggesting that those augmented with mesh are associated with a lower recurrence rate. We aimed to explore the suggestion that the established use of mesh does indeed lower the rate of operation for recurrence in a single National Health Service region. Method We collected retrospective Office of Population Censuses and Surveys coded data across one region of all primary and recurrent inguinal hernia repairs over 15 years (2004–2019). Electronic records of recurrent repairs were scrutinised to identify year and type of previous primary repair. Results In total, 7,234 repairs were performed during this time, of which 289 (4%) were for symptomatic recurrence. Operations for primary repair increased year on year (111 in 2004 to 402 in 2019). Frequency of operation for recurrent herniation declined with increasing use of mesh (8.8% in 2004 to 3.5% in 2019). The majority of repairs (73%) for recurrence were by an open approach. As opposed to an open mesh repair, a primary laparoscopic repair was associated with an earlier recurrence. Conclusions Inguinal hernia repairs are increasing in frequency but operations for later symptomatic recurrence following an open primary prosthetic mesh repair are not

Resistance training enhances delayed memory in healthy middle-aged and older adults: A randomised controlled trial

Objectives High-intensity exercise is a potential therapeutic tool to postpone or prevent the onset of cognitive decline. However, there is a lack of sufficient evidence regarding the longitudinal effects of structured resistance training on cognitive function in healthy adults. The purpose of this study was to investigate the effect of two ecologically valid, intense 12-week resistance training programs on cognitive function in late middle-aged adults. Design Single-site parallel randomised controlled trial at the Department of Exercise Science strength and conditioning laboratory. Groups allocated by minimisation randomisation. Methods Forty-five healthy adults (age range = 41-69 years) were enrolled and randomised into A.) high-load, long rest resistance training (n = 14), or B.) moderate-load, short rest resistance training (n = 15) twice per week for 12 weeks, or a non-exercising control (n = 16). Follow-up within 7 days. Data were collected September 2016-December 2017. Cognitive function assessed using the CogState computerised battery. Assessors were blinded to participant group allocation. Secondary outcomes were maximal muscle strength and body composition. Results Forty-four participants were analysed in 2018. Delayed verbal memory performance was improved (p = 0.02) in resistance training groups (g = 0.67-0.79) when compared to the control group, with no differences between training groups. Likewise, increases in maximal muscle strength were observed (p < 0.01) in resistance training groups when compared to the control group, with no differences between training groups. No differences in body composition were observed. There were no adverse events or side-effects of the intervention. Conclusions 12 weeks of intense resistance training improves delayed verbal memory irrespective of training design (i.e., high-load vs. moderate-load)

The response to iron supplementation of pregnant women with the haemoglobin genotype AA or AS

The influence of haemoglobin genotype on the response to iron supplementation was studied in a randomized, double blind, placebo-controlled trial involving 497 multigravid pregnant women from a rural area of The Gambia. Women were randomly allocated to receive either oral iron (60mg elemental iron per day) or placebo. At 36 weeks of pregnancy, women who had received oral iron during pregnancy had higher mean haemoglobin, packed cell volume, plasma iron and ferritin levels than did women who received placebo. Iron supplementation of pregnant women with the AA haemoglobin genotype also resulted in increases in the packed cell volume (PCV) and haemoglobin level measured after delivery, and in the birth weight of the infant. However, in AS women PCV and haemoglobin level at delivery were lower in the supplemented group and supplementation was also associated with reduced birth weights. In malaria endemic areas, pregnant women with the haemoglobin genotype AS may not benefit from iron supplementation during pregnanc